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답안 #883914

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
883914 2023-12-06T11:40:27 Z chanhchuong123 Lampice (COCI19_lampice) C++14
110 / 110
 1923 ms 14456 KB 
#include <bits/stdc++.h>
using namespace std;
#define task ""
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()

const int MOD = 1e9 + 7;
const int MAX = 50005;
const int BASE = 256;
int n;
int len;
char cc;
int maxH;
int sz[MAX];
char a[MAX];
int pw[MAX];
bool rem[MAX];
vector<int> adj[MAX];
unordered_map<int, bool> mp[MAX];

int dfsSZ(int u, int p) {
    sz[u] = 1;
    for (int v: adj[u]) if (v != p && !rem[v]) {
        sz[u] += dfsSZ(v, u);
    }
    return sz[u];
}

int findCentroid(int u, int p, int n) {
    for (int v: adj[u]) if (v != p && !rem[v]) {
        if ((sz[v] << 1) > n)
            return findCentroid(v, u, n);
    }
    return u;
}

void dfs(int u, int p, bool upd, int h, int up, int dw, bool &found) {
    up = (1LL * up * BASE + (a[u] - 'a' + 1)) % MOD; dw = (dw + 1LL * pw[h - 1] * (a[u] - 'a' + 1)) % MOD;
    int value = (1LL * pw[len - h] * dw - up + MOD) % MOD;
    if (upd) mp[h][value] = true;
    else {
        if (h + 1 == len && (1LL * dw * BASE + (cc - 'a' + 1)) % MOD == up) {
            found = true;
            return;
        }
        if (len > h && mp[len - h - 1].find(value) != mp[len - h - 1].end()) {
            found = true;
            return;
        }
    }
    if (h < len) {
        for (int v: adj[u]) if (v != p && !rem[v]) {
            dfs(v, u, upd, h + 1, up, dw, found);
            maxH = max(maxH, h + 1);
            if (found) return;
        }
    }
}

void solve(int u, int p, bool &found) {
    int c = findCentroid(u, p, dfsSZ(u, p)); rem[c] = true;

    maxH = 1;
    cc = a[c];
    for (int v: adj[c]) if (v != p && !rem[v]) {
        dfs(v, c, 0, 1, a[c] - 'a' + 1, 0, found);
        if (found) return;
        dfs(v, c, 1, 1, a[c] - 'a' + 1, 0, found);
    }
    for (int i = 0; i <= maxH; ++i) {
        mp[i].clear();
    }

    for (int v: adj[c]) if (v != p && !rem[v]) {
        solve(v, u, found);
        if (found) return;
    }
}

bool ok(int x) {
    for (int i = 0; i <= n; ++i) mp[i].clear();
    memset(rem, false, sizeof rem);
    bool found = false; len = x;
    solve(1, -1, found);
    return found;
}

int main() {
	ios_base::sync_with_stdio(false); cin.tie(nullptr);

	if (fopen(task".inp", "r")) {
		freopen(task".inp", "r",  stdin);
		freopen(task".out", "w", stdout);
	}

    cin >> n;
    cin >> (a + 1);
    for (int i = 1; i < n; ++i) {
        int u, v; cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    pw[0] = 1; for (int i = 1; i <= n; ++i) {
      pw[i] = 1LL * pw[i - 1] * BASE % MOD;
    }
    int ans = 1;
    for (int i = 0; i < 2; ++i) {
        int l = 0, r = n / 2 + 1;
        while (r - l > 1) {
            int mid = l + r >> 1;
            if (ok(i + 2 * mid)) l = mid; else r = mid;
        }
        ans = max(ans, i + 2 * l);
    }
    cout << ans;
	return 0;
}

Compilation message

lampice.cpp: In function 'int main()':
lampice.cpp:110:25: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  110 |             int mid = l + r >> 1;
      |                       ~~^~~
lampice.cpp:92:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   92 |   freopen(task".inp", "r",  stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
lampice.cpp:93:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   93 |   freopen(task".out", "w", stdout);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
17.0 / 17.0

# 결과 실행 시간 메모리 Grader output
1 Correct 3 ms 4736 KB Output is correct
2 Correct 5 ms 4700 KB Output is correct
3 Correct 17 ms 4696 KB Output is correct
4 Correct 18 ms 4696 KB Output is correct
5 Correct 1 ms 4700 KB Output is correct
6 Correct 1 ms 4700 KB Output is correct
7 Correct 1 ms 4956 KB Output is correct

Subtask #2
25.0 / 25.0

# 결과 실행 시간 메모리 Grader output
1 Correct 749 ms 13152 KB Output is correct
2 Correct 773 ms 13504 KB Output is correct
3 Correct 545 ms 13396 KB Output is correct
4 Correct 668 ms 14024 KB Output is correct
5 Correct 1010 ms 14456 KB Output is correct
6 Correct 139 ms 13652 KB Output is correct

Subtask #3
31.0 / 31.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1465 ms 10416 KB Output is correct
2 Correct 1923 ms 9936 KB Output is correct
3 Correct 1606 ms 10660 KB Output is correct
4 Correct 1576 ms 10240 KB Output is correct
5 Correct 1195 ms 9460 KB Output is correct
6 Correct 1178 ms 9248 KB Output is correct

Subtask #4
37.0 / 37.0

# 결과 실행 시간 메모리 Grader output
1 Correct 3 ms 4736 KB Output is correct
2 Correct 5 ms 4700 KB Output is correct
3 Correct 17 ms 4696 KB Output is correct
4 Correct 18 ms 4696 KB Output is correct
5 Correct 1 ms 4700 KB Output is correct
6 Correct 1 ms 4700 KB Output is correct
7 Correct 1 ms 4956 KB Output is correct
8 Correct 749 ms 13152 KB Output is correct
9 Correct 773 ms 13504 KB Output is correct
10 Correct 545 ms 13396 KB Output is correct
11 Correct 668 ms 14024 KB Output is correct
12 Correct 1010 ms 14456 KB Output is correct
13 Correct 139 ms 13652 KB Output is correct
14 Correct 1465 ms 10416 KB Output is correct
15 Correct 1923 ms 9936 KB Output is correct
16 Correct 1606 ms 10660 KB Output is correct
17 Correct 1576 ms 10240 KB Output is correct
18 Correct 1195 ms 9460 KB Output is correct
19 Correct 1178 ms 9248 KB Output is correct
20 Correct 892 ms 7772 KB Output is correct
21 Correct 1002 ms 8540 KB Output is correct
22 Correct 1514 ms 8908 KB Output is correct
23 Correct 352 ms 7136 KB Output is correct
24 Correct 1287 ms 8884 KB Output is correct
25 Correct 1212 ms 8236 KB Output is correct
26 Correct 1593 ms 10452 KB Output is correct
27 Correct 1597 ms 9164 KB Output is correct
28 Correct 1049 ms 7260 KB Output is correct
29 Correct 1103 ms 7504 KB Output is correct
30 Correct 1240 ms 9556 KB Output is correct
31 Correct 1105 ms 8284 KB Output is correct
32 Correct 1002 ms 10644 KB Output is correct
33 Correct 758 ms 8832 KB Output is correct